The invention relates to an apparatus and a method for the condition-dependent maintenance of hydrostatic displacement units.
When hydraulic plants cease operating as a result of maintenance work or a malfunction, cost-intensive down-time during which replacement parts must be exchanged is the result. Furthermore, down-time can cause contamination of the whole hydraulic circuit, so that the entire plant must be cleaned before being put back into service, and the hydraulic oil, together with system components such as filter elements, must be exchanged. If hydraulic plants are not in operation, for example, in a production line, this results not only in reduced productivity but also in very high costs for shutting down and restarting the hydraulic plant.
According to the prior art, in order to reduce failures a hydraulic plant should be so equipped that it can also be controlled over relatively long distances.
For example, a pump unit comprising a pump and an electric motor which drives the pump is known from DE 100 18 866 A1. A digital motor control system is provided for the electric motor, which control system is connected via a bus to a digital communication unit which has an interface based on Internet protocols, so that the pump unit is ultimately controllable via a digital network, an intranet or the Internet.
A disadvantage of the prior art emerging from DE 100 18 866 A1 is that the pump unit is not controlled directly, but via the motor control system which is remotely operable via the digital communication unit. The pump unit itself has at least one sensor, such as a pressure sensor, a differential pressure sensor or a temperature sensor, the output signal of which can be interrogated via the communication unit. However, data relating directly to operation of the pump or the pump unit, such as surface vibration of the housing and the contamination level of the hydraulic fluid, is not detected in the pump unit according to the document DE 100 18 866 A1. This gives rise to the disadvantage that the data acquired and transmitted for determining service intervals is insufficient, because relevant data such as the average amplitude of housing surface vibration, or the abraded material contained in the hydraulic fluid, is not acquired in the pump unit according to the document DE 100 18 866 A1.